Related Concept Videos

Criticisms of the Evolutionary Perspective01:23

Criticisms of the Evolutionary Perspective

In a study where individuals posing as strangers offered compliments and proposed casual sex to students, the responses differed significantly based on gender. Not a single woman accepted the proposal, while 70% of the men agreed. This outcome provides a useful scenario to explore through the lens of evolutionary psychology and social learning theory, highlighting the diverse perspectives on human sexual behaviors.
Evolutionary psychology provides one explanation for these findings, suggesting...
Parental Care00:55

Parental Care

Many animals exhibit parental care behavior, including feeding, grooming, and protecting young offspring. Parental care is universal in mammals and birds, which often have young that are born relatively helpless. Several species of insects and fish, as well as some amphibians, also care for their young.
Hardy-Weinberg Principle01:49

Hardy-Weinberg Principle

Diploid organisms have two alleles of each gene, one from each parent, in their somatic cells. Therefore, each individual contributes two alleles to the gene pool of the population. The gene pool of a population is the sum of every allele of all genes within that population and has some degree of variation. Genetic variation is typically expressed as a relative frequency, which is the percentage of the total population that has a given allele, genotype or phenotype.In the early 20th century,...
Epistasis Analysis01:09

Epistasis Analysis

Although Mendel chose seven unrelated traits in peas to study gene segregation, most traits involve multiple gene interactions that create a spectrum of phenotypes. When the interaction of various genes or alleles at different locations influences a phenotype, this is called epistasis. Epistasis often involves one gene masking or interfering with the expression of another (antagonistic epistasis). Epistasis often occurs when different genes are part of the same biochemical pathway. The...
Nondisjunction01:21

Nondisjunction

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate correctly and move to the opposite poles of the cells. This produces daughter cells with abnormal chromosome numbers.  Nondisjunction is common during anaphase I or anaphase II of meiosis.  Mutations in synaptonemal complex proteins that attach homologous chromosomes increase the chances of nondisjunction in anaphase I of meiosis I. In contrast, mutations in topoisomerases and condensins that hold sister...
Nondisjunction01:29

Nondisjunction

During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed sister chromatid separation during meiosis II. In some species, notably plants, nondisjunction can result in an organism with an entire additional set of chromosomes, which is called polyploidy. In humans, nondisjunction can occur during male or female gametogenesis and the resulting gametes possess one too many or one too few chromosomes.